Commit e5687f2f authored by Kirill Smelkov's avatar Kirill Smelkov

context: Don't hardcode that contexts are always done with canceled error

We'll need to mark contexts that miss their deadline with
deadlineExceeded error in a follow-up patch.

In this patch: transform _BaseCtx._cancel to accept an error with which
a context has to be canceled, but for now always use canceled in places
where _cancel is called.
parent 58ba1765
......@@ -71,7 +71,7 @@ deadlineExceeded = RuntimeError("deadline exceeded")
# the context is no longer needed.
def with_cancel(parent): # -> ctx, cancel
ctx = _CancelCtx(parent)
return ctx, ctx._cancel
return ctx, lambda: ctx._cancel(canceled)
# with_value creates new context with key=value.
#
......@@ -95,7 +95,7 @@ def with_value(parent, key, value): # -> ctx
# https://godoc.org/lab.nexedi.com/kirr/go123/xcontext#hdr-Merging_contexts
def merge(parent1, parent2): # -> ctx, cancel
ctx = _CancelCtx(parent1, parent2)
return ctx, ctx._cancel
return ctx, lambda: ctx._cancel(canceled)
# --------
......@@ -150,17 +150,17 @@ class _BaseCtx(object):
return None
# _cancel cancels ctx and its children.
def _cancel(ctx):
return ctx._cancelFrom(None)
def _cancel(ctx, err):
return ctx._cancelFrom(None, err)
# _cancelFrom cancels ctx and its children.
# if cancelFrom != None it indicates which ctx parent cancellation was the cause for ctx cancel.
def _cancelFrom(ctx, cancelFrom):
def _cancelFrom(ctx, cancelFrom, err):
with ctx._mu:
if ctx._err is not None:
return # already canceled
ctx._err = canceled
ctx._err = err
children = ctx._children; ctx._children = set()
if ctx._done is not None:
......@@ -177,13 +177,13 @@ class _BaseCtx(object):
# propagate cancel to children
for child in children:
child._cancelFrom(ctx)
child._cancelFrom(ctx, err)
# propagateCancel establishes setup so that whenever a parent is canceled,
# ctx and its children are canceled too.
def _propagateCancel(ctx):
pdonev = [] # !nilchan .done() for foreign contexts
pforeignv = [] # parents with !nilchan .done() for foreign contexts
for parent in ctx._parentv:
# if parent can never be canceled (e.g. it is background) - we
# don't need to propagate cancel from it.
......@@ -195,27 +195,27 @@ class _BaseCtx(object):
if isinstance(parent, _BaseCtx):
with parent._mu:
if parent._err is not None:
ctx._cancel()
ctx._cancel(parent._err)
else:
parent._children.add(ctx)
else:
if _ready(pdone):
ctx._cancel()
ctx._cancel(parent.err())
else:
pdonev.append(pdone)
pforeignv.append(parent)
if len(pdonev) == 0:
if len(pforeignv) == 0:
return
# there are some foreign contexts to propagate cancel from
def _():
_, _rx = select(
ctx._done.recv, # 0
*[_.recv for _ in pdonev] # 1 + ...
ctx._done.recv, # 0
*[_.done().recv for _ in pforeignv] # 1 + ...
)
# 0. nothing - already canceled
if _ > 0:
ctx._cancel()
ctx._cancel(pforeignv[_-1].err())
go(_)
......
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